On February 25, 2021, we met with 15 Department of Natural Resources representatives from across the state, just north of Ford, Washington. Our goal was to demonstrate how our modular panel kiln can be assembled around existing piles of residual biomass, often referred to as slash piles. Our demonstration was designed to inform DNR reps on the feasibility of utilizing Biochar conversion to remove residual fuels from the forest, sequester carbon and create a soil amendment to enhance forest health.
Every Biochar event offers an opportunity for experimentation and education. This time was no different. The recent burn offered an opportunity to pyrolyze a slash pile larger than any we have pyrolyzed previously in conditions that also presented a challenge. The wood biomass was both wet, frozen and significantly larger in diameter than prior burns. This presented an ignition challenge. However, once top lit, the pile pyrolyzed nicely and created a good amount of Biochar. Even with heat lost to thawing and drying the wood, we reached temperatures exceeded 1000° F.
We were able to demonstrate that even large diameter biomass can be converted by Biochar, removing fuels and sequestering carbon. Larger diameter feedstock was not completely converted but was significantly charred on the outside. Due to freezing conditions, some of the large diameter that was charred on the outside was still frozen in the middle. In fact, some of the wood at the bottom of the kiln still had frost on it, even with kiln temperatures reaching 1000° F. This demonstrates the kilns ability to focus heat. Following quenching the Biochar with water, we were able to dig under the Biochar and uncover cold fertile undamaged soil, quite different from sterile ash/mineral soil following traditional slash pile burning.
Fire or combustion of fuel, requires three components, heat, fuel and oxygen. This is often represented by the Fire Triangle. In the presence of heat and fuel, we limit the amount of oxygen allowed to come in contact with the fuel and we alter the process to pyrolysis. In this limited oxygen environment, we burn off wood gas and are left with latent, or non reactive, carbon that remains stable for centuries and is removed from the carbon cycle.
Removing carbon from the carbon cycle is a necessity to capture legacy carbon, introduced by human activity, that lingers in the atmosphere as a greenhouse gas.
Biochar created by pyrolzying biomass instead of simply burning or combusting it is sterile and adheres to nutrients in its microscopic pores, binding to and retaining nutrients when added to the soil. Biochar also absorbs water like a sponge retaining moisture. Moisture and nutrient retention increase soil health and mitigate moisture loss due to our changing climate. Both necessities for sustained forest health